1. Field of the Invention
The present invention relates to a boat propulsion device.
2. Description of the Related Art
There are two types of engines for boat propulsion devices: engines which use spark plugs in a coil-on-plug configuration, and engines which use spark plugs in a double ended ignition coil configuration. For example, Japan Patent Laid-open Patent Publication JP-A-02-230965 discloses an engine provided with an ignition device with a coil-on-plug configuration.
In the coil-on-plug configuration, an ignition coil is incorporated with a spark plug, and controlling the conduction of current through each ignition coil controls the spark timing for each spark plug independently. On the other hand, in a double ended ignition coil configuration the ignition coil and spark plug are separate. The plurality of spark plugs in a double ended ignition coil configuration is connected to the same ignition coil via a cable. Controlling the conduction of current through the shared ignition coil ensures that multiple spark plugs will spark simultaneously with great accuracy.